What does the theory of plate tectonics maintain?这板块构造学说的理论讲些什么?Geologists describe the motion of the plates and the consequences of such motion as plate tectonics.地质学家把板块运动及这种运动所造成的后果看作是板块构造运动.The idea of sea - floor sp...
在半导体收音机中晶体管代替了真空管.In semiconductor receivers transistors take the place of vacuum tubes.与老式真空管相比,晶体管具有许多优点.Transistors have many advantages over the old - fashioned vacuumtube valves.真空管或显影管都未破碎.No vacuum or picture tube...